Bomb disposal expert Yeung Yat-Sing, Ivan, (Kevin Cheng) returns from England to visit relatives and he comes across a grenade case by accident. Ivan's skills are highly appreciated by Senior Chemist Ko Yin-Pok (Bobby Au-Yeung) and he is invited to join the Forensic Division. Ivan soon becomes the division's rising star. Sing gets back in touch with his long-lost best friend Koo Chak-Sam (Frankie Lam). Sam serves as a forensic writer and he is going to get married soon.

During a case, Sam's fiancée Lam Ding-Ding (Linda Chung) and Pok's police girlfriend Leung Siu-Yau (Yoyo Mung) are caught in an explosion meant to kill two drug dealers. Ding-Ding dies of her injuries, while Siu-Yau loses movement in her right hand and goes half-deaf. Yau's duties are passed to Ma Kwok-Ying (Charmaine Sheh) from the Narcotics Bureau. Both Sam and Ivan find Kwok-Ying extremely charming with her smart and unfathomable characteristics in case handling.

Integrating laboratory techniques, logical reasoning, and forensic knowledge, the trio strive to fight against crimes tremendously. As they get to know each other more and more, the entangled triangle of love also starts to hinder their working relationships. Cases includes "The Skeleton", "The Case of the Disabled", "The Movie Star Mystery", and many more. The forensic scientists went through different ways to solve each of those cases.

At the end of the series, Ivan and Ma Kwok-Ying end up in a car crash while chasing a fugitive, but through that experience, Ivan knows that Ma Kwok-Ying is committed to him, with her efforts to pull him out of the car in which they were trapped in. In the end, Ivan suffers from an explosion by a bomb planted by a fugitive to get revenge on Kwok-Ying, which leads him into a coma. Kwok-Ying was greatly upset. The fugitive was tricky and tried to capture Kwok-Ying at the police station. The fugitive mostly appears eating dried ginger. After the last case, Tim and Siu Yau get married. During the wedding, Ivan wakes up, although the frame only shows Ma Kwok-Ying receiving a call on her mobile phone, then running ecstatically, while crying, from the wedding, ripping her dress as she did in the first episode to aid running. The remaining wedding crowd finds out, and runs after Kwok-Ying to see Ivan.